Decorative laminates are widely employed in the building industry as counter and table tops, bathroom and kitchen work surfaces, furniture and cabinets, wall paneling, partitions, doors, wallpaper, book covers, map and label stock. High-pressure decorative laminates are laminated articles comprising plural layers of synthetic resin impregnated paper sheets consolidated or bonded together into a unitary structure under heat and pressure. Conventionally, the decorative or print layer is a sheet of high quality purified alpha cellulose fiber and/or certain rayon fibers impregnated with a thermosetting condensation resin such as aminotriazine aldehyde resins, for example melamine formaldehyde resins. An overlay sheet, transparent when cured, may be employed to protect the decorative or print layer and is also a sheet of alpha cellulose, or the like, impregnated with an aminotriazine aldehyde. The overlay and print sheets are bonded to a plurality of core or body sheets of fibrous cellulosic material, usually kraft paper, most generally impregnated with a thermosetting phenol-formaldehyde resin.
The major portion of the paper in a decorative laminate is composed of the core or body sheets rather than the print or overlay sheets. Typically seven or eight core sheets are consolidated with only a single print and single overlay sheet to form a conventional 1/16 inch decorative laminate.
Although the core sheets are less expensive than the print or overlay sheets, it is apparent that the core sheets are a significant cost factor, because of their volume in a decorative laminate. Typically from three to nine core sheets of 30 to 130 pound/per ream (3000 ft.sup.2) paper are used in the preparation of decorative laminates. It is also apparent that the properties of the core stock paper which depending on the resins employed will influence the properties of the end product decorative laminate.
U.S. Pat. Nos. 3,220,916, 3,218,225, and 3,589,974 describe phenol-formaldehyde resins which are used to impregnate kraft core sheets in the production of high pressure decorative laminates. U.S. Pat. Nos. 3,938,907 and 3,975,572 describe the use of a mixture of melamine-formaldehyde and acrylic resins, and U.S. Pat. No. 4,473,613 describes a mixture of a thermoset blend of a phenol-formaldehyde resin, a cross-linked acrylic resin and a melamine-formaldehyde resin which are used to impregnate core sheets in the production of decorative laminates.
U.S. Pat. No. 4,659,595 describes saturated paper products, particularly masking tape, which are prepared by saturating cellulose fibers with an aqueous emulsion. The aqueous emulsion is prepared by the emulsion polymerization of (a) a vinyl ester of an alkanoic acid, (b) ethylene, (c) an N-methylol containing copolymerizable monomer, (d) an alkenoic acid or an alkenedioc acid, and (e) a surfactant.
Conventional anionic surfactants and nonionic surfactants are typically used to control the latex particle size and to stabilize the latexes at high solid content. Such conventional surfactants are physically absorbed onto the surface of the particles, in dynamic equilibrium with the water phase. However, the surfactants are not covalently bound to the polymer particles. Under high shear or under a few cycles of freeze-thaw tests, the surfactants can be desorbed and their stabilizing properties are lost. Using greater amounts of conventional surfactants may improve stability but high levels of such surfactants introduce significant quantities of ionic species into the polymer, often adversely affecting film properties, particularly water sensitivity due to the hydrophilicity imparted by the surfactant and the tendency of the unbound surfactant to dissolve in water throughout the film.